Setting mechanism for snap action circuit breaker

Abstract

A circuit breaker comprising an electrically insulating housing, an overcurrent sensor in the housing, a stationary and a movable contact in the housing, and a latch mechanism coupled to the movable contact. The latch mechanism is tripped in response to a sensed overcurrent; an overcenter spring is coupled to the movable contact for opening and closing the contacts with a snap action when the latch mechanism is tripped. An elongated handle member extends through a handle opening in the housing and is movable axially between a contacts open position and a contacts closed position. Handle link means couples the handle member to the latch mechanism and translates a longitudinal movement of the handle member into a rotational movement of the handle link to urge the latch mechanism into the contacts closed position. The handle link means is also operable to retain the handle member in its second position upon manual movement of the handle member from its first to its second position and for permitting tripping of the latch mechanism and opening of the contacts independently of movement of the handle member. The handle member also has means associated therewith to inhibit rotational movement of the handle member while permitting longitudinal movement.

What is claimed is: 
     
       1. A circuit breaker comprising an electrically insulating housing; an overcurrent sensor in said housing; a stationary and a movable contact in said housing; a latch mechanism coupled to said movable contact, and means for tripping said latch mechanism in response to a sensed overcurrent and for moving said latch mechanism between contacts open and contacts closed positions; means, including an overcenter spring, coupled to said movable contact for opening and closing said contacts with a snap action; a handle opening in said housing; an elongated handle member extending through said handle opening; means for permitting longitudinal axial movement of said handle member while inhibiting rotational movement thereof between a first, contacts open position and a second, contacts closed position; handle link means coupling said handle member to said latch mechanism, said handle link means being operative to translate a substantially linear movement of said handle member into a rotational movement of said link means for urging said latch mechanism into said contacts closed position, said handle link means being operable to retain said handle member in its second position upon manual movement of the handle member from its first to its second position and for permitting tripping of said latch mechanism and opening of said contacts independently of movement of said handle member; and means normally biasing said handle member toward said first, contacts open position when said latch mechanism is tripped by said overcurrent sensor. 
     
     
       2. A circuit breaker according to claim 1, further comprising a flat guide rail extending downwardly from the inner top face of the housing adjacent said handle opening, said handle having means thereon which cooperate with said flat guide member to take up rotational torsion forces inparted to said elongated handle member. 
     
     
       3. A circuit breaker according to claim 2, wherein said handle member comprises an elongated rod which is slotted at one end to pivotably mount said handle link means, and a pair of flat parallel flange members extending from said rod opposite sides of and adjacent to said guide rail, the space between said flange members being slightly greater than the thickness of said guide rails to permit free longitudinal movement of said flanges and said rod along the length of said rail, one of said flanges engaging said rail when a rotational or twisting force is exerted on said handle rod. 
     
     
       4. A circuit breaker according to claim 1 or 3, wherein said handle link means comprises a first member coupled to said latch mechanism through a first pivot mount and to said frame at a second pivot mount, and a second member pivotably coupled at one end to said elongated handle member and at its other end to a third pivot mount intermediate said first and second pivot mounts. 
     
     
       5. A circuit breaker according to claim 4, wherein the angle subtended by the arc bounded on one side by a first straight line through the center of said first and second pivot points and on the other side by a second straight line through the centers of the second and third pivot points is less than 90°. 
     
     
       6. A circuit breaker according to claim 5, wherein said angle is greater than 45°. 
     
     
       7. A circuit breaker according to claim 6, wherein said angle is less than 55°. 
     
     
       8. A circuit breaker according to claim 1 or 3, wherein said handle member has a flanged extension at its outer end portion to permit manually grasping said handle member for manually moving said member to its contacts open position. 
     
     
       9. A circuit breaker according to claim 1 or 3, wherein the top of said handle member lies flush with said handle openings in said contacts closed position and extends outwardly from said opening in the contacts open position.